Recasting FRSA Whistleblower Law: Contributing‑Factor Causation and Retaliatory Hostile Work Environment After Ziparo v. CSX Transportation

I. Introduction

In Ziparo v. CSX Transportation, Inc., No. 23‑262 (2d Cir. Nov. 25, 2025), the Second Circuit delivers a significant opinion reshaping Federal Railroad Safety Act (FRSA) whistleblower litigation in three principal ways:

• It holds that the Supreme Court’s decision in Murray v. UBS Securities, LLC, 601 U.S. 23 (2024), applies fully to FRSA claims because both FRSA and Sarbanes‑Oxley (SOX) incorporate the same AIR‑21 burden‑shifting framework. As a result, an FRSA plaintiff need not prove retaliatory intent, animus, or motive to satisfy the statutory “contributing‑factor” causation standard.
• It overrules key portions of the Second Circuit’s own prior decision in Tompkins v. Metro‑North Commuter Railroad Co., 983 F.3d 74 (2d Cir. 2020), including the rule that temporal proximity is necessarily insufficient to prove causation and the requirement of some proof of “retaliatory motive.” Sufficiently close temporal proximity can, standing alone, satisfy contributing‑factor causation.
• For the first time, it explicitly recognizes a retaliatory hostile work environment as a cognizable adverse employment action under the FRSA and adopts the Burlington Northern/Carr “would dissuade a reasonable worker” standard for such claims, rather than the stricter “severe or pervasive” harassment standard.

On the facts, the panel (Judges Sack, Nardini, and Pérez) vacates the district court’s second grant of summary judgment for CSX. It holds that:

• A reasonable jury could find that CSX subjected conductor Cody Ziparo to a retaliatory hostile work environment before his formal ethics complaint in May 2016; and
• There are genuine disputes of material fact as to whether his whistleblowing contributed to his July 2016 termination and whether CSX can carry its heavy “clear and convincing” burden to show it would have terminated him even absent any protected activity.

The case is remanded for trial, and the opinion will now be a leading authority on FRSA causation, the scope of protected activity, and the availability of hostile‑work‑environment theories in safety‑statute retaliation cases.

II. Summary of the Opinion

The court’s opinion proceeds in four main steps:

1. Statutory framework: The court first confirms that the FRSA’s enforcement provision, 49 U.S.C. § 20109(d), incorporates the AIR‑21 burden‑shifting framework and its “contributing‑factor” causation standard into all enforcement actions, including “kickout” suits filed directly in federal district court when the Department of Labor (DOL) has not acted within 210 days.
2. Effect of Murray on FRSA precedent: Relying on Murray, the court:
   • Overrules Tompkins’s requirement that FRSA plaintiffs produce evidence of the employer’s retaliatory intent or animus to prove causation; and
   • Rejects Tompkins’s categorical rule that temporal proximity is necessarily insufficient to establish a genuine factual issue on retaliation.
   A plaintiff may satisfy the contributing‑factor element with circumstantial evidence, including sufficiently close temporal proximity alone.
3. Hostile work environment under FRSA: The court holds that a retaliatory hostile work environment is a cognizable “adverse employment action” under § 20109(b). Borrowing from Title VII retaliation jurisprudence, the court adopts the Burlington Northern standard as elaborated in Carr v. NYC Transit Auth., 76 F.4th 172 (2d Cir. 2023): an aggregation of retaliatory acts that “well might have dissuaded a reasonable worker” from engaging in protected activity is actionable.
4. Application to Ziparo:
   • The court finds evidence from which a jury could conclude that Ziparo engaged in protected activity (good‑faith safety complaints) as early as April 2016, not only when he called the ethics hotline on May 4.
   • It holds that his supervisors’ escalating scrutiny, selective discipline, daily berating, and threat to fire him for not falsifying records could constitute a retaliatory hostile work environment caused, at least in part, by his safety complaints.
   • As to the June 9 switch misalignment and subsequent termination, the court concludes that a jury could find his protected activity contributed to the decision to fire him, especially given:
     • documented hostility by his supervisors,
     • their involvement (or knowledge) in the termination process,
     • close temporal proximity, and
     • the fact that only 6 of 17 similarly charged employees were terminated.
   • Because of this disparate treatment, CSX has not shown, as a matter of law, by clear and convincing evidence that it would have terminated an otherwise identical employee who had not engaged in protected activity.

The court therefore vacates the grant of summary judgment and remands for further proceedings.

III. Detailed Analysis

A. Factual and Procedural Background in Context

1. The workplace conflict

From 2006 to 2016, Cody Ziparo worked as a freight train conductor for CSX in upstate New York. In early 2016, trainmasters Ryan Van Blarcom and Jim Lacy began pressuring conductors, including Ziparo, to falsify CSX’s internal “on‑board work order” (OBWO) records to make performance metrics look better and thereby increase the trainmasters’ bonus compensation.

The OBWO system tracks completion of switching and placement work for both operational and customer‑service purposes; it is not legally mandated and is not itself a safety device. However, the pressure to falsify records manifested in several ways:

• Near‑daily demands on Ziparo to mark tasks “complete” that were not actually finished.
• Unusually intense scrutiny of his work, including Van Blarcom driving 1 hour 45 minutes from Massena to Watertown to watch him switch cars for almost seven hours a day.
• Demands that he keep handwritten logs of every task and endure lengthy daily phone calls in which he was berated for OBWO entries.

Both Ziparo and engineer Christopher Pigula complained informally and repeatedly to Lacy and Van Blarcom that the falsification demands and harassment were causing stress, distraction, and unsafe conditions. According to their testimony, these complaints were made “multiple times” and “at least three days a week” in the weeks leading up to April 2016, and they explicitly framed the problem as a safety issue.

2. Escalating discipline and the May 2016 ethics complaints

On April 13, 2016, after this series of complaints, Van Blarcom charged Ziparo for allegedly failing to perform a “handbrake test” on railcars. There was evidence that such tests had not routinely been enforced and that the charge was selectively brought against Ziparo. Lacy later declared that Van Blarcom had a practice of “watch[ing]” an employee he wanted to eliminate until he could stack up serious violations—a practice contrary to CSX policy.

After April 13, the pressure intensified:

• For approximately 2½ weeks, Ziparo had to submit a handwritten log of all his activities, and each morning he endured an hour‑long phone call in which Van Blarcom “reamed” and “chewed” him out, leaving him “shaking” and “anxiety‑ridden.”
• On April 29, when the crew worked through breaks but could not complete all assigned work within their hours‑of‑service limit, Van Blarcom and Lacy instructed him to mark the unfinished work as “complete” anyway. He refused and correctly marked it “out of time.”

On May 3, 2016, Lacy called him into his office, “screamed and yelled,” and told him that Van Blarcom wanted him fired for “insubordination” for refusing to falsify OBWOs. During that encounter, Ziparo again explicitly warned that this pressure and harassment were causing a “safety issue” because workers were too stressed and distracted to focus.

The next day, May 4, he and Pigula each called CSX’s ethics hotline. CSX’s internal summary recorded that he reported the falsification demands and stated they were a “safety issue because employees are not focused on their work and are preoccupied with the harassment coming from Jim [Lacy] and Ryan [Van Blarcom].”

CSX’s investigation substantiated:

• that Lacy and Van Blarcom had instructed Ziparo to falsify OBWOs, and
• that Lacy had threatened to charge him with insubordination for refusing.

Lacy was disciplined, and Van Blarcom received a written warning.

3. The June 9 switch incident and termination

On June 9, 2016—about a month after the ethics complaints—a southbound train struck a misaligned mainline switch, causing serious damage. Evidence indicated that:

• Ziparo had been the last person to operate the switch.
• He failed to return the switch to normal position.
• There was no evidence that anyone else touched the switch.

While the southbound movement merely damaged the switch, the opinion notes that a northbound movement over the same misalignment could have fully derailed, with potentially catastrophic consequences.

CSX investigated, suspended his conductor certification, and held an investigative hearing on June 16. At that hearing:

• Van Blarcom served as charging officer against Ziparo.
• Brian Murray served as hearing officer.
• Assistant Division Manager Jerry Lewandowski signed the June 13 charge letter; according to Lacy, he had told Lacy that he was “watching” Ziparo after the ethics complaint.
• Division Manager Bill Sester, who was aware of the ethics complaint and CSX’s internal discipline of the supervisors, made the decision to terminate.

On July 15, 2016, Murray found him responsible for the switch misalignment, and Sester terminated his employment. Evidence showed that, in comparable switch‑violation cases, only 6 of 17 employees had been terminated; most were not fired.

4. Litigation history

• Administrative stage: In August 2016, Ziparo filed an FRSA complaint with the DOL. After 210 days passed without final agency action, he invoked the FRSA “kickout” provision and filed suit in federal court.
• Ziparo I (N.D.N.Y. 2020): The district court granted summary judgment for CSX, holding that he had not engaged in “protected activity” because his belief about a safety hazard was not objectively reasonable.
• Ziparo II (2d Cir. 2021): The Second Circuit reversed, holding that § 20109(b)(1)(A) requires only a subjective good‑faith belief that a condition is hazardous—not objective reasonableness—and that complaints about stress and distraction can qualify if made in good faith.
• Remand and Ziparo III (N.D.N.Y. 2023): On remand, the district court again granted summary judgment, now holding that:
  • his protected activity was limited to the two complaints in early May 2016;
  • he did not prove causation between that activity and his termination; and
  • even if he had, CSX had proven by clear and convincing evidence that it would have terminated him anyway.
• Current appeal (2025): After the parties briefed the appeal, the Supreme Court decided Murray v. UBS Securities, rejecting a retaliatory‑intent requirement in SOX/AIR‑21 cases. The Second Circuit then decided Murray on remand. In this opinion, the court applies Murray to FRSA and revisits its own precedent in Tompkins.

B. The Statutory Framework: FRSA, AIR‑21, and SOX

1. FRSA and its 2007 amendments

The FRSA’s purpose is “to promote safety in every area of railroad operations.” 49 U.S.C. § 20101. Congress strengthened the statute’s whistleblower protections in 2007, intending to:

• provide “administrative and civil remedies for employees,”
• improve “transparency and accountability of the railroad carriers,” and
• “ensure that employees can report their concerns without the fear of possible retaliation.”

Section 20109(b)(1)(A), the provision at issue, prohibits a railroad from discharging, demoting, suspending, reprimanding, or “in any other way discriminat[ing]” against an employee for “reporting, in good faith, a hazardous safety or security condition.”

2. Enforcement and the “kickout” mechanism

Enforcement is governed by § 20109(d):

• The employee must first file a complaint with DOL/OSHA.
• If no final decision issues within 210 days (not due to the employee’s bad faith), the employee may file an “original action” in federal district court for “de novo review” under § 20109(d)(3). This is the “kickout” provision.
• Crucially, § 20109(d)(2) states that “[a]ny action brought under paragraph (1)”—which includes kickout suits—“shall be governed by the rules and procedures, and the legal burdens of proof, set forth in section 42121(b).” Section 42121(b) is the AIR‑21 whistleblower provision.

The Second Circuit reads this text to mean that the AIR‑21 burden‑shifting framework and causation standard apply in all FRSA enforcement actions, including federal kickout suits. This reading aligns with every other circuit to address the question and rejects CSX’s argument that the less plaintiff‑friendly “but‑for” causation standard should govern in district court.

3. The AIR‑21 two‑step framework

AIR‑21, 49 U.S.C. § 42121(b)(2)(B), sets up a two‑step process:

1. Employee’s prima facie case (step one): The employee must prove by a preponderance of the evidence that:
   • (1) he engaged in protected activity;
   • (2) the employer knew of the protected activity;
   • (3) he suffered an unfavorable personnel action; and
   • (4) the protected activity was a contributing factor in that unfavorable action.
2. Employer’s affirmative defense (step two): If the employee satisfies step one, the burden shifts and remains with the employer. The employer must prove, by clear and convincing evidence, that it would have taken the same unfavorable action in the absence of the protected activity. It is not enough to show it could have; it must show it would have.

This is a more plaintiff‑friendly regime than the familiar McDonnell Douglas three‑step framework used in many Title VII cases, where the burden of persuasion remains on the employee. Here:

• the employee’s causation burden is lighter (“contributing factor,” not “but‑for” or “motivating factor”), and
• the employer’s burden is heavier (“clear and convincing,” not mere articulation of a legitimate reason).

C. Precedents and Authorities Considered

1. Tompkins v. Metro‑North and the pre‑Murray split

Before Murray, circuits split over whether a whistleblower had to prove retaliatory intent to satisfy contributing‑factor causation:

• The Third and Ninth Circuits, in cases like Araujo v. NJ Transit Rail Operations, 708 F.3d 152 (3d Cir. 2013), and Frost v. BNSF Railway Co., 914 F.3d 1189 (9th Cir. 2019), held that no showing of retaliatory motive was required. Temporal proximity could suffice.
• The Seventh and Eighth Circuits (Armstrong v. BNSF Ry., Kuduk v. BNSF Ry., Gunderson v. BNSF Ry.) required some evidence of intent or animus and were skeptical of temporal proximity alone.

In Tompkins, the Second Circuit aligned with the Seventh/Eighth Circuit view. It held that:

• FRSA plaintiffs must show “some proof of retaliatory motive” and “evidence of intentional retaliation,” and
• they must show “more than a temporal connection” to establish causation, relying heavily on a set of five “highly relevant facts” drawn from Gunderson (e.g., disciplinary process details, involvement of allegedly hostile actors, administrative outcomes).

Tompkins thus imposed a significantly higher causation burden on FRSA plaintiffs than the statutory text suggests.

2. Murray v. UBS Securities and its extension to FRSA

In Murray, the Supreme Court interpreted SOX’s whistleblower provision, which explicitly incorporates the same AIR‑21 framework used in FRSA. The Court held:

• No retaliatory‑intent element. The statute does not require proof of “retaliatory intent” or animus. The word “discriminate” does not inherently require such a state of mind element.
• Employee’s burden on intent is satisfied through contributing‑factor causation. Congress decided that the employee must only show that protected activity was a contributing factor; this is how the statute gets at intent, without making animus a separate element.
• “Contributing factor” is broad and lenient. It means that protected activity must “have a share in bringing about” the unfavorable action—it must “actually cause or help cause” the decision, but it can be a small part of the employer’s reasoning.
• Burden‑shifting—not extra elements—is the mechanism for distinguishing lawful from unlawful conduct. The clear‑and‑convincing affirmative defense is the employer’s opportunity to show that it would have acted the same way for legitimate reasons.

Because FRSA and SOX both adopt the AIR‑21 burdens, the Second Circuit treats Murray as controlling on FRSA causation standards. This is the central doctrinal move in Ziparo.

3. Administrative Review Board (ARB) and other authorities

The opinion is heavily informed by:

• ARB decisions under AIR‑21/SOX, such as:
  • DeFrancesco v. Union Railroad Co. (on the limited role of “legitimate reasons” at the prima facie stage),
  • Speegle v. Stone & Webster Construction (on removing not only the protected activity but also “facts logically connected” to it when analyzing the counterfactual at step two),
  • Menendez v. Halliburton (on the need for a legitimate, non‑retaliatory reason extrinsic to the protected activity), and
  • Fordham v. Fannie Mae (on the scope of the employer’s clear‑and‑convincing burden).
• Title VII cases for guidance on:
  • how temporal proximity can establish prima facie causation (Zann Kwan, Banks, Gorman‑Bakos, Gorzynski),
  • the definition of a retaliatory adverse action (Burlington Northern & Santa Fe Ry. Co. v. White), and
  • the broader standard for retaliatory hostile work environment in Carr.

D. The Court’s Legal Reasoning

1. AIR‑21 applies fully in FRSA kickout actions

Responding to CSX’s argument that AIR‑21 should apply only in administrative proceedings but not in federal court kickout actions, the Second Circuit turns to the statutory text:

• Section 20109(d)(1) allows any employee alleging discharge, discipline, or other discrimination in violation of § 20109(a), (b), or (c) to “seek relief in accordance with the provisions of this section.”
• Section 20109(d)(2) states that “[a]ny action brought under paragraph (1)” is governed by the “rules and procedures” and “legal burdens of proof” of AIR‑21.
• Section 20109(d)(3) describes the federal court lawsuit as an “original action” for “de novo review” but does not supply a different causation or burden‑shifting regime.

Reading these provisions together, the court concludes:

• The kickout action is simply another enforcement “action” under § 20109(d)(1).
• The statute therefore incorporates AIR‑21’s framework and standards into federal kickout cases, just as it does for agency proceedings.
• CSX’s reading would yield the “odd” result that the same statutory claim is governed by two different causation standards depending solely on how quickly the DOL acts—something Congress is unlikely to have intended.

The court also notes that § 20109(d)(1) explicitly covers claims under § 20109(b)—the very provision protecting safety reports like those made by Ziparo—foreclosing any suggestion that § 20109(b) claims are subject to a different standard.

2. Re‑defining “contributing‑factor” causation under FRSA

Applying Murray, the court squarely overrules critical causation holdings in Tompkins:

• FRSA plaintiffs do not need to prove retaliatory intent, motive, or animus to meet their causation burden. Those concepts may be part of the evidence, but they are not elements.
• Temporal proximity is not categorically insufficient; sufficiently close timing between protected activity and an adverse action can, by itself, permit a reasonable jury to find that the activity “contributed” to the action.
• Courts are not required to “balance” the five Gunderson factors as an analytic template for causation; at most, those factors can serve as optional guideposts among many forms of circumstantial evidence.

The court emphasizes:

• A “contributing factor” is any factor that, alone or in combination with others, has an actual effect that “helps bring about” the adverse decision. It must be more than conduct that merely “tends to affect” decisions in general, but its contribution can be small.
• FRSA, like other AIR‑21 statutes, does not set any category of evidence (e.g., temporal proximity) as categorically inadequate. Direct and circumstantial evidence are equally acceptable.
• Given that even stricter causation standards (e.g., Title VII’s “but‑for” causation for retaliation) allow temporal proximity to prove prima facie causation, it would be anomalous to impose a higher evidentiary bar under the more lenient contributing‑factor standard.

3. Recognizing a retaliatory hostile work environment under FRSA

The FRSA forbids a railroad from discharging, demoting, suspending, reprimanding, “or in any other way discriminat[ing]” against an employee for protected activity. The court reasons:

• The “normal definition” of “discrimination” is “differential treatment,” i.e., treating someone worse because of a protected characteristic or activity.
• A hostile work environment created in retaliation for safety complaints is one form of “in any other way discriminat[ing] against an employee.”
• FRSA, like Title VII’s anti‑retaliation provision, is not textually limited to actions that affect “terms, conditions, or privileges of employment” (a limitation found in Title VII’s anti‑discrimination, but not anti‑retaliation, provision). Therefore, the Burlington Northern standard, not the “severe or pervasive” test, is appropriate.

Accordingly, the court borrows the Burlington Northern/Carr formulation: for an FRSA retaliatory hostile work environment claim, the employee must show that the allegedly retaliatory acts, taken together, were materially adverse—meaning that they “well might have dissuaded a reasonable worker” from engaging in protected activity.

4. Application to the hostile environment claim

The district court had restricted “protected activity” to the May 3–4 complaints, concluding that earlier conduct involved merely “experiencing” hazardous conditions, not “reporting” them. The Second Circuit corrects this:

• Ziparo II held that FRSA protects any report made in good‑faith belief that a condition is hazardous, including informal, internal complaints.
• There is deposition testimony that well before May 2016, Ziparo and Pigula explicitly told Lacy and Van Blarcom that the falsification pressures and harassment were causing a “safety issue” and creating an “unsafe environment.”
• Although Lacy and Van Blarcom dispute (or minimize) the timing and content of these complaints, those conflicts create classic fact issues for a jury.

Once the protected activity is properly dated to April 2016 or earlier, a jury could find that CSX subjected him to a retaliatory hostile environment:

• Unusual scrutiny (daily observation, detailed logs) shortly after the complaints.
• Selective discipline (the April 13 handbrake charge) after the complaints and testimony that this was atypical.
• Daily berating phone calls that left him “shaking” and “anxiety‑ridden.”
• Lacy’s May 3 outburst and threat of termination for refusing to falsify OBWOs.

The court holds that this combination of actions—viewed in the light most favorable to the plaintiff—could reasonably be found to be materially adverse and capable of dissuading a reasonable employee from making safety complaints. The lack of physical violence or threats of violence is not dispositive.

5. Application to the termination claim

As to the termination, three points are central.

a. Protected activity and knowledge

It is undisputed that:

• Safety‑framed complaints on May 3 and the May 4 ethics hotline call are protected activity under § 20109(b)(1)(A), given the Second Circuit’s prior holding in Ziparo II (subjective good‑faith standard).
• CSX knew of these complaints: Lacy and Van Blarcom were directly involved; the ethics investigation led to discipline of both; and senior managers (Murray and Sester) knew of the complaints and resulting discipline.
• Termination is an “unfavorable personnel action.”

b. Contributing‑factor causation

The remaining question is whether there is sufficient evidence for a jury to conclude that his protected activity contributed to the termination decision. The court identifies several strands of evidence:

• Hostility and participation. CSX concedes that “the record shows that Van Blarcom and Lacy exhibited some hostility or antagonism towards Ziparo.”
  • That hostility coincides with, and appears triggered by, his refusal to falsify OBWOs and his complaints that the demands were causing safety problems.
  • Hostile actors (notably, Van Blarcom) participated directly in the post‑incident proceedings (as charging officer), and senior managers aware of the complaints played decision‑making roles.
• Temporal proximity. Only about two months separate the May complaints and the July 15 termination. Courts have routinely held that such proximity can support an inference of causation at the prima facie stage, particularly when combined with other evidence.
• Inconsistent discipline of comparators. Only 6 of 17 employees charged with comparable rule violations were terminated. The fact that the company usually did not fire employees for similar conduct allows a jury to infer that something else—possibly the whistleblowing—helped cause the harsher treatment of Ziparo.

The court stresses that causation at step one does not require showing that the protected activity was the only or even the primary reason for termination. It is enough if it “played only a very small role” in the decision. On this evidentiary record, a reasonable juror could so conclude.

6. Clarifying the employer’s affirmative defense

On the employer’s side, the opinion significantly clarifies the scope and rigor of the step‑two defense:

• The employer must show, by clear and convincing evidence, that it would have (not merely could have) taken the same action in a world where the protected activity (and facts logically tied to it) did not occur.
• It must rely on a legitimate, non‑retaliatory business reason that is extrinsic to the protected activity. Reasons that themselves rest on unlawful objectives (e.g., punishing a refusal to commit fraud) cannot support the defense.
• Where the employer’s own records show inconsistent application of rules—such as firing only a minority of similarly situated employees—a jury can reasonably doubt that it is “highly probable” the company would have fired this particular employee absent his whistleblowing.

Specifically, the court:

• Rejects as a matter of logic and policy the suggestion that CSX could rely on hostility toward his refusal to falsify records as an independent justification to discipline him; that is itself unlawful and intertwined with his safety complaints.
• Emphasizes, via ARB precedents, that in constructing the counterfactual (“in the absence of protected activity”), a fact‑finder must remove not only the protected act itself but also intertwined facts that flow from it (e.g., the tension and animosity generated by unheeded safety complaints).
• Declines to grant CSX any “business judgment” deference at step two; that concept does not dilute the explicit statutory standard of clear‑and‑convincing proof.

Given the comparative disciplinary data and evidence of hostility, the court holds that CSX has not carried its burden as a matter of law. Whether the company would have fired an otherwise identical, non‑whistleblowing conductor for the June 9 incident is a question for the jury.

E. The Role of Evidence and Summary Judgment Under the New Standard

Taken together, the opinion materially changes how FRSA summary judgment motions must be analyzed in the Second Circuit:

• No categorical exclusions. Temporal proximity, inconsistent discipline, hostile remarks, shifting explanations, and other circumstantial evidence can, alone or in combination, satisfy step‑one causation. Courts should not impose extra‑textual restrictions on what kinds or combinations of evidence “count.”
• Lower threshold for plaintiffs at step one. The plaintiff need only produce enough evidence that a reasonable jury could find that protected activity had “some share” in bringing about the adverse action.
• Higher threshold for defendants at step two. The clear‑and‑convincing standard, framed as requiring evidence that “instantly tilts the evidentiary scales,” will often make summary judgment on the employer’s affirmative defense inappropriate unless the record is exceptionally one‑sided (e.g., uniformly enforced stand‑alone rules, consistent discipline of all comparators).

In Ziparo itself, these principles result in:

• Rejection of summary judgment on the hostile‑environment theory; and
• Rejection of summary judgment on the termination theory, both as to causation and as to the employer’s affirmative defense.

IV. Impact and Future Implications

A. Alignment with the more protective Araujo/Frost line

By applying Murray and explicitly rejecting the retaliatory‑intent requirement, the Second Circuit brings its FRSA jurisprudence into alignment with the Third and Ninth Circuits’ more protective approach exemplified by Araujo and Frost. This has several practical consequences:

• FRSA plaintiffs in the Second Circuit now enjoy a uniform, lenient causation standard consistent with DOL and ARB practice.
• Defense arguments premised on a “lack of animus” or “no smoking gun of intent” lose their centrality at step one; the analytic focus shifts toward timing, comparators, and process irregularities.

B. Temporal proximity becomes a powerful evidentiary tool

The explicit recognition that sufficiently close temporal proximity alone can satisfy contributing‑factor causation at summary judgment—especially given the lower causation bar—will:

• Empower plaintiffs to survive earlier dispositive motions in many cases where the timing is tight and there is at least some corroborating context; and
• Make it more difficult for employers to obtain early dismissal simply by denying retaliatory motive and pointing to a legitimate explanation.

Courts will still scrutinize whether a significant time gap or an intervening, independent event breaks the causal chain. But in close‑in‑time cases (weeks or a few months), summary judgment will be harder to sustain.

C. Expansion of hostile‑environment theories under safety statutes

By recognizing a retaliatory hostile work environment under FRSA and adopting the Burlington Northern “would dissuade a reasonable worker” standard, the Second Circuit:

• Makes clear that FRSA is not limited to “ultimate” employment actions (firing, demotion) but also covers patterns of harassment, micromanagement, and selective discipline that can chill safety reporting.
• Encourages plaintiffs’ counsel to plead and develop hostile‑environment theories in addition to discrete actions, particularly where whistleblowers face sustained harassment short of termination.

This approach may be influential for other safety‑focused whistleblower statutes with similar “discriminate” language, and it harmonizes safety‑retaliation doctrine with Title VII retaliation jurisprudence in the Second Circuit.

D. Clarification of the employer’s “would have” defense

The opinion puts teeth into the clear‑and‑convincing standard:

• Employers must develop robust comparator evidence and be prepared to show consistent, across‑the‑board enforcement of rules if they hope to prevail on summary judgment.
• Mere assertion of a “legitimate” reason is insufficient; the company must persuade the fact‑finder that this reason alone would have driven the decision even in a hypothetical world with no protected activity or resulting tensions.
• Relying on reasons that are intertwined with the protected activity (e.g., discipline for refusing unsafe or fraudulent practices) is risky and often impermissible.

As a practical matter, more FRSA retaliation claims will likely proceed to trial, particularly where the record reveals mixed motives, inconsistent discipline, or close timing.

E. Reinforcement of subjective good‑faith reporting standard

Although established in Ziparo II, this opinion operates against the backdrop that under § 20109(b)(1)(A):

• An employee’s report is protected so long as he subjectively believes in good faith that a condition is hazardous.
• The report can concern non‑physical conditions—such as stress and distraction from harassment—that the employee believes are undermining safety.

Combined with the now‑clarified causation standard, FRSA is a powerful vehicle for employees who raise internal safety concerns in the railroad industry.

V. Complex Concepts Simplified

For clarity, the following key legal concepts are distilled into simpler terms:

• FRSA (Federal Railroad Safety Act): A federal law aimed at promoting railroad safety. Section 20109 protects railroad employees from retaliation when they report safety concerns or engage in other protected activities.
• AIR‑21: Originally a law for airline whistleblowers. Congress later used its burden‑shifting and causation rules as a template for other whistleblower statutes, including FRSA and SOX.
• Protected activity (in this case): Reporting, in good faith, a “hazardous safety or security condition.” Under Ziparo II, the test is subjective good faith, not objective correctness. Reports can be internal and informal.
• Contributing‑factor causation: The employee’s protected activity does not have to be the main reason, or the “but‑for” reason, for the adverse action. It qualifies if it helped bring about the decision in any real way, even if it played only a small role.
• Burden‑shifting (AIR‑21 framework):
  1. The employee must prove, by a “more likely than not” standard (preponderance of evidence), that the protected activity contributed to the adverse action.
  2. If he does, the employer must prove, by a much stricter “clear and convincing” standard, that it would have taken the same action even if the employee had never engaged in the protected activity.
• Clear and convincing evidence: A high evidentiary bar. The judge or jury must be left with a firm belief that it is highly probable the employer would have taken the same action even without any protected activity.
• Kickout provision: If DOL does not decide the administrative complaint within 210 days (and the delay is not the employee’s fault), the employee can “kick out” of the agency process and file a new, full case in federal court.
• Temporal proximity: How close in time the adverse action is to the protected activity. Short time gaps (e.g., weeks or a few months) can support an inference of retaliation.
• Retaliatory hostile work environment: A pattern of mistreatment (e.g., harassment, heightened scrutiny, unfair discipline) imposed because the employee engaged in protected activity. Under FRSA, as under Title VII retaliation law, the question is whether this pattern would discourage a reasonable worker from reporting safety concerns.
• Comparators: Other employees who engaged in similar conduct (e.g., similar rule violations). If they were treated more leniently, that can suggest retaliation against the plaintiff.

VI. Conclusion

Ziparo v. CSX Transportation is a cornerstone FRSA whistleblower decision in the Second Circuit. It:

• Confirms that the AIR‑21 framework and its “contributing‑factor” causation standard fully govern FRSA claims in federal court, including kickout actions.
• Implements the Supreme Court’s reasoning in Murray by eliminating any requirement that plaintiffs show retaliatory intent or animus and by recognizing that temporal proximity alone can satisfy causation in appropriate cases.
• Recognizes retaliatory hostile work environment as an actionable form of discrimination under FRSA and adopts the Burlington Northern/Carr “would dissuade a reasonable worker” standard.
• Clarifies and strengthens the “clear and convincing” standard governing the employer’s affirmative defense, with particular attention to comparator evidence and the need for reasons extrinsic to the protected activity.

Doctrinally, the opinion shifts FRSA retaliation litigation toward a more plaintiff‑protective, text‑driven model that emphasizes Congress’s judgment that safety concerns should not influence personnel decisions “not even a little bit.” Practically, it will make summary judgment more difficult for railroads in close‑in‑time or mixed‑motive cases and will encourage fuller development of hostile‑environment theories in whistleblower suits.

On remand, a jury—not a judge on summary judgment—will decide whether CSX’s treatment of Cody Ziparo was unlawfully retaliatory and whether the company can persuasively show that it would have fired a similarly situated non‑whistleblower for the June 9 switch incident. Whatever the outcome at trial, the doctrinal holdings in Ziparo will shape FRSA and other AIR‑21–based whistleblower litigation for years to come.